Submitted to: International Society of Root Research Proceedings
Publication Type: Proceedings
Publication Acceptance Date: June 15, 1996
Publication Date: N/A
Technical Abstract: Alternate-furrow irrigation of corn, with fertilizer placement in the non- irrigated furrow, could potentially reduce nitrate leaching and ground water contamination. Experiments in 1994, however, showed that fertilizer nitrogen (N) uptake was reduced when water and N were spatially separated. In 1995, a study was initiated to compare root demographics under alternate eand every-furrow irrigation to determine if reduced fertilizer N uptake in the non-irrigated furrow was due to reduced root growth in the dry soil. Rainfall was well above normal in the spring and early summer of 1995. Early season nitrate movement into lower soil layers occurred in both treatments due to the high rainfall. There was no difference in total fertilizer N uptake between the alternate- and every-furrow treatments, although the pattern of N uptake was affected by irrigation placement. Alternate-furrow irrigation prolonged fertilizer N uptake into the reproductive period, while fertilizer N uptake had ceased by R1 with every furrow irrigation. Alternate-furrow irrigation increased root growth beneath the fertilized and non-fertilized furrows at all growth stages. With alternate-furrow irrigation, greater growth occurred in the wet, non- fertilized furrow compared with the dry, fertilized furrow through the V12 growth stage. After V12, root growth ceased in the irrigated but continued in the non-irrigated furrow. The greatest increase in root biomass between V12 and R1 in the non-irrigated furrow occurred below 60 cm, where water and nitrate availability were high. Late season root growth and fertilizer N uptake in the non-irrigated furrow appeared to have benefitted from early season rains whch carried nitrate into the lowere soil profile.